nuku-nuku
A deeply comfortable warmth, like being wrapped in a blanket or sitting by a heater. Suggests being pampered by warmth.
💡Staying in a heated room on a snowy day — 'I was nuku-nuku under the kotatsu all afternoon.'
こたつの中でぬくぬくしている。
I'm staying nuku-nuku inside the kotatsu.
While it snowed outside, I stayed ___ under the kotatsu.
外は雪なのに、こたつの中で○○していた。